1. Field of the Invention
The present invention relates to a vibration type driving apparatus.
2. Description of the Related Art
Conventionally, there are ultrasonic motors of a vibration type driving apparatus that linearly drive a driven member. For example, Japanese Patent Application Laid-Open No. 06-311765 discusses an ultrasonic motor that excites a plate-like vibrating member with a standing wave having two bending modes to generate elliptic vibration at a predetermined portion of the vibrating member. The ultrasonic motor drives a moving member by bringing the moving member in contact with the predetermined portion.
Moreover, Japanese Patent Application Laid-Open No. 2004-304887 discusses an ultrasonic motor that generates a standing wave having two bending modes that are at right angles to each other to excite a vibrating member having a projection with a raised portion. In such a configuration, an elliptic motion that is generated by the combination of the two bending modes drives a moving member.
In the above-described vibration type driving apparatuses, vibration generated by a vibrating member is realized only in a bending mode. Therefore, the vibrating member can be thinned.
However, there are the following problems in the above-described conventional vibration type driving apparatuses. As described above, the vibration generated by a vibrating member is realized only in the bending mode, so that the vibrating member can be thinned. On the other hand, a pressurization unit that presses the moving member onto the vibrating member or a guide mechanism for regulating the moving direction of the moving member is required. As a result, it is difficult to reduce the size of a vibration type driving apparatus (or an ultrasonic actuator).
Furthermore, to reduce the size of the pressurization unit, a moving member can be formed by a magnet, and the moving member can be pressed onto the vibrating member by magnetic force. However, a vibration type driving apparatus of such a configuration cannot take advantage of non-magnetism, which is one of the features of an ultrasonic actuator.
Additionally, Japanese Patent Application Laid-Open No. 06-311765 discusses a plurality of ultrasonic actuators that do not require a guide mechanism. However, the shape of the vibrating member or the moving member is complex, so that the size of such ultrasonic actuators cannot be sufficiently reduced. Furthermore, such ultrasonic actuators are not easy to manufacture.
Therefore, further improvements may be made by providing a vibration type driving apparatus that can press the moving member onto the vibrating member in a simple configuration, and that can enlarge thrust at the time of driving as well as holding force when power is not fed. Moreover, further improvements may be made by providing a vibration type driving apparatus that can regulate the moving direction of a moving member without providing a special guide mechanism, so that the size can be greatly reduced.